This invention relates to automotive testing devices, and in particular to an apparatus to test the functioning of a Hall effect device without requiring removal from the vehicle.
Many late model motor vehicle ignition systems include a Hall effect device mounted in the ignition distributor. In use in that manner generally the device replaces the "ignition points" or "contact points" of older models as an electrical switch to separate the spark for each cylinder. Moreover, Hall effect devices are finding much wider uses throughout the auto industry, in applications as varied as anti-lock braking systems and fuel timing systems. Up to the present time, however, in the event that a problem arose wherein the Hall effect device was suspected to be defective, there was no easy way to test the Hall effect device to determine whether it worked, short of replacing it, or at least removing it for testing. Since these Hall effect devices are generally epoxied or otherwise formed into a larger part, removing or replacing the Hall effect device meant a large disassembly job, with the attendant waste of time and money if the Hall effect device was not at fault. Clearly, some easier means of testing the Hall effect device would be desirable.
Other apparatus denominated as testing circuits for Hall effect devices, such as those shown in Thompson, U.S. Pat. No. 4,488,112, Daley, U.S. Pat. No. 4,491,794 and Van Husen, U.S. Pat. No. 4,514,687, are not directed to this particular usage. Rather, they are provided for the purpose of testing the operate and release time and point failures of Hall effect devices, and include variable magnetic fields, measuring the voltage of the Hall effect device. Hence these devices are prohibitively expensive for wide usage in the auto repair industry. Further, they do not address the problem of requiring removal before testing.
This invention relates to improvements to the apparatus described above and to solutions to the problems raised or not solved thereby.